The room was actually R100 per night, not R84 as per the HI website. I stayed for 4 nights.
They were kind enough to charge me the R84 per night, but should really be reimbursed the difference (R16 a night, times 4 nights = R64) by HI. My credit card has also been charged a deposit and booking fee, they never received their deposit, so I should get that refunded to my credit card.
I am not the only person who got mis-informed by the HI website, this should really be looked at.